Soft heating device

ABSTRACT

A soft heating device such as a heat blanket, heat cushion or heat feather-bed, having at least one heating cord arranged on a base heating element, a connection cable for an energy supply connected by an externally insulated connecting means, and a control circuit. The heating device has a robust structure because the connecting means are grouped together in a connecting unit comprising a common carrier plate and/or a common encapsulating element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a supple heating device, such as a heatingblanket, heating pad or heated mattress pad, having at least one heatercord arranged on a base heating element, a connecting cable for energysupply connected by a connecting device insulated toward the outside,and a control circuit.

2. Discussion of Related Art

A heating device is disclosed, for example, by German Patent ReferenceDE 101 26 066 A1, in which a connection between a heater cord and aconnecting cable is shown in edge areas of a base heating element, forexample a blanket. Besides the heater cord with the heating wirescontained therein, further structural components of the electricalcircuit can be arranged, such as in the edge areas of the blanket, suchas with a fuse and an indicator element, for example with wiring. It ispossible to provide a rectifier arrangement between the ends of the twoheating wires of the heater cord which are remote from the connectingcable. A control circuit has at least one on/off switch, with even amulti-stage switch, and can comprise further components.

A heating device is taught by European Patent Reference EP 0 562 850 A2,wherein the heater cord, which also has two coaxial heating wires, forexample, is connected via two connecting terminals with a connectingcable, over whose length a control circuit is arranged. The controlcircuit has a special safety system, which has a rectifier device in theform of a diode arranged between the heating wires at the end of theheater cord remote from the connecting end, a fuse in the controlcircuit, which can be thermally triggered. During normal operations, thediode which is arranged in series between the heating wires lets only ahalf-wave of the supply current through, but if a short circuit occursin the heating wires the negative half-wave of the heating current islet through and is then conducted via a further rectifier arrangement inthe control circuit of a resistor arrangement, which is thermallycoupled with a fuse responsive to a temperature increase and triggersthe fuse in case of a short circuit in the heating wires. The controlcircuit also comprises a control member in the form of a thyristor fortemperature regulation.

With heating devices of this type dependable assembly and functioningare of particular importance.

SUMMARY OF THE INVENTION

One object of this invention is to provide a supple heating device ofthe type mentioned above but in which a dependable assembly andfunctioning are achieved, or at least furthered.

This object is achieved with a connecting device combined into aconnecting unit which has a common support plate and/or a commonencapsulating element.

Thus there is increased dependability because of the simple clear designof critical connecting points.

Here, the connecting unit can be arranged on the base heating elementand is fixed in place by a holding device.

Definite mounting characteristics are achieved if the support plate isdesigned as a board with printed strip conductors, and the supportingplate supports several connecting elements of the connecting device,some of which are connected with an associated heating conductor andsome which are connected with an associated lead of the connecting cableand to the extent provided are connected with each other by stripconductors for creating respective current paths.

If the heater cord has two heating conductors, which are connected atthe one cord end with associated leads of the connecting cable and atthe other cord end are electrically connected with each other directlyor via a rectifier arrangement contained in the connecting unit, bothcord ends can be simply connected and wired.

A structure which is advantageous for mounting and functioning isachieved because a current safety fuse included in the connecting unitis arranged in the supply current circuit.

The steps wherein the encapsulation element is provided by encasing orby two assembled shell elements contribute further to safety. In thiscase the insulating material is matched to the particular safetyrequirements in regard to a cast or injection-molded encapsulatingelement and in regard to one embodiment as a shell wherein, because ofthe increased contact resistance, the insulating properties and steps inconnection with plug or clamped or crimped connections are matched tohigher requirements than soldered connections, for example.

With a simple construction, critical points in the heating cord and theconnecting cable are dependably protected because the encapsulatingelement has at least one cord guidance device formed thereon for theheater cords, and a cable guidance device for the formed on connectingcable.

Further advantageous measures which contribute to safety include theencapsulating element made of an elastic plastic material, at least inthe area of each cord guidance device and/or of the cable guidancedevice, and is melt-resistant to at least 150° C., as well asflame-resistant and resistant to tensile strain.

Those steps contribute to simple mounting and the provision of adependable contact, wherein the connecting device is designed forinserting and clamping one or both heater cord ends in place withelectrical contact, and wherein, on its side facing the connectingdevice, a cover element has formed-out places, which work together withthe connecting device so that the clamping-in-place occurs when puttingthe shell elements together.

A rigid, tensile strain-resistant arrangement is assisted because theconnecting unit is fixed in place on the base heating element by fixingthe associated connecting cable end and/or at least one cord end inplace.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is explained in greater detail in view of exemplaryembodiments and making reference to the attached drawings, wherein:

FIG. 1 shows a supple heating device with a connecting unit between theheater cord and the connecting cable, in a schematic view;

FIG. 2 is a schematic view of a support plate of a connecting unit;

FIG. 3 is a schematic view showing an embodiment of a connecting sectionof a heater cord;

FIGS. 4A and 4B show two different embodiments of encapsulatedconnecting units in schematic views;

FIG. 5 is a perspective open plan view of one embodiment of a connectingunit;

FIG. 6 shows schematic views of various connecting means; and

FIGS. 7 a-7 c show different enlarged views of connecting devices, eachin a cross section.

DESCRIPTION OF PREFERRED EMBODIMENTS

A supple heating device 1 with a heater cord 3, which is inserted in ameander shape in a supple base element 2, for example a blanket, a pador a mattress pad, with a connecting cable 5, which can be connected toa supply voltage by a plug 7, and having a length arranged controlcircuit 6 and a connecting unit 4 arranged between the heater cord 3 andthe connecting cable 5 in an edge area of the base element 2, isschematically represented in FIG. 1. As shown in FIG. 4B, differentheating zones can be established on the base element 2 by at least onefurther heater cord 3′, which is placed on the base element 2.

As customary, the heater cord 3, 3′ advantageously has two heatingconductors made of electric resistance wire, which are arranged,insulated from each other, in the heater cord 3, 3′, as shown in FIG. 2,for example. An advantageous, known per se, embodiment has one heatingwire as the outer conductor 3.2, and the other heating wire as the innerconductor 3.4 extending in the heater cord 3, 3′ coaxially in relationto each other, are electrically insulated from each other by anintermediate insulation 3.3, are insulated toward the exterior by anouter insulation 3.1 and are wound in a coil shape. During current flowthrough the two heating conductors 3.2, 3.4 in opposite directions, acompensation of their electromagnetic fields is achieved. The innerconductor 3.4 is wound on an insulating core. As a so-called lanstranded conductor, it can also have several strands and is thenparticularly flexible and interruption-resistant.

As FIG. 2 shows, the cord end 3.5 at the side of the connecting cableand the cord end 3.6 facing away from it are both electrically wired andmechanically fixed in place on a support plate 4.1 of the connectingunit 4, wherein connections to the inner conductor 3.4 and the outerconductor 3.2 are also provided. Direct contact can be provided betweenthe outer conductor 3.2 and the inner conductor 3.4, particularly at thecord end 3.6 remote from the connecting cable 5 or, as shown in FIG. 2,a rectifier arrangement in the form of one or several semiconductordiodes 8 can be provided. Also, other or additional electricalcomponents can be connected between the outer conductor 3.2 and theinner conductor 3.4 on the support plate 4.1, such as shown in the twopublications mentioned above, for example.

The cord end 3.5 at the side of the connecting cable is connected withthe outer conductor 3.2 and the inner conductor 3.4 at associated leads5.1, 5.2 of the connecting cable. A fuse element 9, for example acurrent fuse, can be arranged on the support plate 4.1 between one lead,for example 5.1, and a heating conductor, for example the outerconductor 3.2. The connection between the leads 5.1, 5.2 of theconnecting cable 5 and the outer conductor 3.2 and the inner conductor3.4 is provided by strip conductors 4.12 located on the side of thesupport plate 4.1 remote from the component side. In this case it ispossible to use wire nails, holding lugs, supporting vanes or crimpconnectors or the like as a connecting device or connecting means 10, asshown in FIGS. 5, 6 and 7, for providing an electrical connectionbetween the outer conductor 3.2 and the inner conductor 3.4 on one sideof the support plate 4.1, and they can be connected with the stripconnectors 4.12 on the opposite side of the support plate 4.1. Thecomponents 8, 9, as well as the contact of the leads 5.1, 5.2 of theconnecting cable 5 with the outer connector 3.2, or inner connector 3.4can be correspondingly provided, which is known per se for a printedcircuit board assembly. Clamping, crimping, soldering or weldingconnections can be used for contacting. The connecting cable 5 isconnected with the base element 2, protected against tensile strain, byfixing devices 2.1, for example sewn or welded to it, in order toprevent the connecting cable 5 or the connecting unit 4 from being tornoff. The heater cords 3, 3′ can be fastened on the base element 2, andthe connecting unit 4 can be fixed in place on the base element 2. Inone embodiment the mechanical connection between the base element 2 andthe connecting unit 4 is in the form of a clip.

The clip has several functions, it can be used for tensile strain reliefof the connecting cable 5, as fixation in place of the connecting unit4, and therefore also as tensile strain relief of each heater cord 3,3′, as a kinking protection of the connecting cable 5 in differentembodiments, for example as a trumpet-shaped outlet opening, cablebushing, or the like, as a cover of the cable exit from the base element2, or as a support for user information, logos, technical data,identification plates, or the like. The clip can be made of differentmaterials, for example plastic, metal or a combination thereof. In oneembodiment of the clip, snap-in hooks are provided, which aresimultaneously used as penetrating tools through at least one coverlayer of the base element 2 and can also provide a locking connection ofthe connecting unit 4. For a savings in tool expense, the clip is forexample constructed so that self-locking can take place by two identicalparts which are rotated by 180° with respect to each other.Alternatively the clip can be of one or several parts containing, forexample, a sort of film hinge, which permits kinking.

The rectifier elements 8, and further possible electrical components,can work together with further electrical circuit components of thecontrol circuit 6 for forming a temperature-regulating circuit and/or asafety system, for example as described in the publications previouslymentioned.

FIG. 3 shows one embodiment of a connecting section of the heater cord3, 3′. In this case a coupling element 3.7 is placed on the heater cordend 3.5, 3.6, for example by some type of screw connection or clamping,which has windows cut out over half its side, one of which exposes theouter connector 3.2 by omitting the outer insulation 3.1, and the otherexposes the inner conductor 3.4 by omitting the outer insulation 3.1 ofthe outer connector 3.2 and the intermediate insulation 3.3. It ispossible with the coupling element 3.7 to make an electrical contact asa coaxial plug with a complementarily embodied counter-element. Thecoupling element 3.7 can be contained in a connecting unit 4, such as anencapsulating element 4.3 of the latter, such as represented in FIGS.4A, 4B and 5. In one embodiment of such a connection, wherein thecoupling element 3.7, or the plug element of the heater cord 3 is pushedonce into the counter-element of the connecting element and is snappedinto, is no longer releasable, or wherein the connecting cable 5, whichhas one or several corresponding counter-elements, can be removed, forexample for washing the heating device in a washing machine. In oneembodiment, one side of the plug element has a one-sided short circuitof the heater cord 3 between the inner conductor 3.4 and the outerconductor 3.2. The connecting element then functions as a tensile strainrelief of the heater cord 3, 3′.

The encapsulation represented in FIGS. 4A and 4B is produced by castingtechnology, wherein a heat-resistant, tensile strain-resistant andfire-resistant, hard-to-ignite insulating medium, which advantageouslyis also washable and water-tight, is completely cast around the supportplate 4.1 with the assembled parts arranged thereon, such as structuralcomponents, connecting cable end and cord ends 3.5, 3.6. The meltingresistance advantageously lies at least at 150° C., advantageously above160° C. or 170° C., so that it assuredly resists occurring temperatures.A permanent melting resistance above 100° C. is assured. If, in spite ofdependable contacting steps, contact resistance should occur and lead toheating, danger is prevented by the encapsulating element 4.2. Sealingcord guides 4.21, or a cable guide 4.22, for the cord ends 3.5, 3.6 andthe connecting cable 5, which provide assured kinking protection for theheater cord 3, 3′ or the connecting cable 5, is formed in one piece onthe encapsulating element 4.2, which is preferably made of an elasticinsulation medium.

A connecting unit 4 for a heating device 1 with two heater cords 3, 3′is represented in FIG. 4B, wherein the connectors as shown in FIG. 2 canbe twice provided. It is also possible to select different ways of theconnection of the two heater cords 3, 3′, such as described inconnection with FIG. 2. For example, it would be conceivable to operateone heater cord with a temperature-control circuit with safety systems,such as in the prior art mentioned above, or respective furtherdevelopments known per se, and the other heater cord with a simplertriggering circuit. In every case the connecting unit 4 permits a safe,definite connection of the heater cords 3, 3′ with the connecting cable5, if desired via structural components used in connection with thisarrangement.

FIG. 5 shows a further exemplary embodiment of a connecting unit 4. Inthis case the encapsulating element 4.3 is put together from two shellelements which can be brought into tight connection with each other,namely a lower element 4.31 and a cover element 4.38 (see FIG. 7), whichhave securing elements 4.33, for example in the form of blind boreopenings, and cooperating counter-securing elements in the form ofmatched protrusions. Clamping or snap-in connections, or sealing,adhesive or welded connections are also suitable. The structure can alsoadvantageously have a two-component plastic material with a harder coresection and a more pliable, sealing cover. A center section of theencapsulating element 4.3 receives the support plate 4.1, while a cordguide device 4.34 formed on the center section with tensile strainrelievers 4.35 is used for routing in the heating cords 3, 3′, and acable guide device 4.32 formed on the center section for securelybringing in the connecting cable 5. For the definite positioning of thesupport plate 4.1 it has lateral positioning elements 4.11 in the formof recesses, which are engaged by matching counter-positioning elements4.36 arranged on the center section of the encapsulating element 4.3.For obtaining tensile strain relief and sealing, the cable guide device4.32 has a clamping element 4.37 for the connecting cable 5.Furthermore, clamping and contacting connecting means 10 are provided onthe support plate 4.1 for the cord ends 3.5, 3.6, or their outerconductor 3.2 and inner conductor 3.4. A fuse element 9 and/or arectifier device 8 in accordance with the previous embodiments asdescribed can be arranged on the support plate 4.1.

FIGS. 6 and 7 show various examples for the design of the connectingmeans 10 and their contacting arrangements. In accordance with FIG. 6,stamped-out and bent sheet metal elements are brought into contact withthe inner conductor 3.4 of the heater cords 3, 3′ as the firstconnecting element 10.1, on the outer conductor 3.2 as the secondconnecting element 10.2, and as a further connecting element 10.3 with astructural component, for example the fuse element 9 or thesemiconductor device in the form of a diode 8, wherein the secondconnecting element 10.2 and the further connecting element 10.3 arearranged on the same sheet metal element. For producing a directconnection, or a short circuit, between the inner conductor 3.4 and theouter conductor 3.2 at one cord end 3.6, the first connecting element10.1 and the second connecting element 10.2 can be connected with eachother via a conducting bridge 10.4. As the two sectional views A-A andB-B, as well as the view C in the left representation in FIG. 6 show,the outer conductor 3.2 and the inner conductor 3.4 are first insertedinto an open clamping connector, which thereafter is bent shut, whilethe connectors of the structural elements 8 or 9 are clamped in a typeof intersecting connection on the further connecting element 10.3.

As the figure sequence of FIGS. 7 a and 7 b shows, the clampingconnection can be produced so that, for example, the cover element 4.38of the encapsulating element 4.3 has recesses, which act together withthe free ends of the connecting elements 10.1, 10.2, and becomenarrower, and whose flanks press the free ends of the connectingelements 10.1, 10.2 together when pushing on the cover element 4.38.FIG. 7 a shows the still open, and FIG. 7 b shows the pressed-on stateof the cover element 4.38, while FIG. 7 c shows the pressed-on statewithout a connecting means 10 inserted. In this case the connectingmeans 10 can be inserted into the encapsulating element 4.3 seated on asupport plate 4.1, or directly without one.

Soldering and welding connections in general make lesser demands on theconstructive solutions for the contact connections. In the simplestcase, all components of the connecting unit can be soldered on a plateor on metallic conducting elements or welded. For example, the crimpingdevices of the heater cord contacting can be omitted, and for fasteningthe electric resistance wires it is only necessary to provide solderingpins in various embodiments for being wound-on and soldered. Forexample, the soldering pins or nails in a rectangular or other form canbe pre-mounted on a board or in the plastic material. One advantage ofrectangular soldering pins over round soldering pins is that theelectrical resistance wire digs into the sharp corners and is lesslikely to slip, until the connection is soldered.

The connecting unit 4 can also be designed for receiving further ordifferent components, for example, it can contain circuit elements of asafety device, such as described in detail in German Patent Reference DE102 11 142 A1, for example further diodes, temperature safety devices,resistor elements triggering the latter in case of heat,temperature-regulating elements, time function elements,temperature-monitoring elements, or a switching unit, or combinations ofsuch elements.

1. A supple heating device (1), including one of a heating blanket, aheating pad and a heated mattress pad, having at least one heater cord(3, 3′) arranged on a base heating element (2), a connected connectingcable (5) for energy supply via a connecting device (10) which areinsulated toward an outside, and a control circuit (6), the suppleheating device comprising: the connecting device (10) combined into aconnecting unit (4) having at least one of a common support plate (4.1)and a common encapsulating element (4.3).
 2. The device in accordancewith claim 1, wherein the connecting unit (4) is arranged on the baseheating element (2) and is fixed in place by a holding device (2.1). 3.The device in accordance with claim 2, wherein the support plate (4.1)is a board with printed strip conductors and supports several connectingelements (10.1, 10.2, 10.3) of the connecting device (10), which are oneof connected with an associated heating conductor (3.2, 3.4) andconnected with an associated lead (5.1, 5.2) of the connecting cable (5)and are connectible with each other by strip conductors (4.12) forcreating respective current paths.
 4. The device in accordance withclaim 3, wherein the at least one heater cord (3, 3′) has two heatingconductors (3.2, 3.4) connected at one cord end (3.5) with associatedleads (5.1, 5.2) of the connecting cable (5) and at an other cord end(3.6) are electrically connected with each other one of directly and viaa rectifier arrangement (8) contained in the connecting unit (4).
 5. Thedevice in accordance with claim 4, wherein a current safety fuse (9)included in the connecting unit is arranged in a supply current circuit.6. The device in accordance with claim 5 wherein the encapsulationelement (4.3) is provided by encasing or by two assembled shell elements(4.31, 4.38).
 7. The device in accordance with claim 6, wherein that theencapsulating element (4.3) has at least one cord guidance device (4.21)formed on for the heater cords (3, 3′), and a cable guidance device(4.22) for the formed on connecting cable (5).
 8. The device inaccordance with claim 7, wherein the encapsulating element (4.3) is ofan elastic plastic material, at least near at least one of the cordguidance device (4.21) and the cable guidance device (4.22), ismelt-resistant to at least 150° C, is flame-resistant and is resistantto tensile strain.
 9. The device in accordance with claim 8, wherein theconnecting device (10) is for inserting and clamping in place withelectrical contact at least one of the heater cord ends (3.5, 3.6), andon a side facing the connecting device (10) a cover element (4.38) hasformed-out places which work together with the connecting device (10) sothat clamping in place occurs while putting the shell elements (4.31,4.38) together.
 10. The device in accordance with one claim 9, whereinthe connecting unit (4) is fixed in place on the base heating element(2) by fixing in place at least one of the associated connecting cableend and at least one cord end (3.5, 3.6).
 11. The device in accordancewith claim 1, wherein the support plate (4.1) is a board with printedstrip conductors and supports several connecting elements (10.1, 10.2,10.3) of the connecting device (10) which are one of connected with anassociated heating conductor (3.2, 3.4) and connected with an associatedlead (5.1, 5.2) of the connecting cable (5) and are connectible witheach other by strip conductors (4.12) for creating respective currentpaths.
 12. The device in accordance with claim 1, wherein the at leastone heater cord (3, 3′) has two heating conductors (3.2, 3.4) connectedat one cord end (3.5) with associated leads (5.1, 5.2) of the connectingcable (5) and at an other cord end (3.6) are electrically connected witheach other one of directly and via a rectifier arrangement (8) containedin the connecting unit (4).
 13. The device in accordance with claim 1,wherein a current safety fuse (9) included in the connecting unit isarranged in a supply current circuit.
 14. The device in accordance withclaim 1, wherein the encapsulation element (4.3) is provided by encasingor by two assembled shell elements (4.31, 4.38).
 15. The device inaccordance with claim 14, wherein the encapsulating element (4.3) has atleast one cord guidance device (4.21) formed on for the heater cords (3,3′), and a cable guidance device (4.22) for the formed on connectingcable (5).
 16. The device in accordance with claim 1, wherein theencapsulating element (4.3) is of an elastic plastic material, at leastnear at least one of the cord guidance device (4.21) and the cableguidance device (4.22), is melt-resistant to at least 150° C., isflame-resistant and is resistant to tensile strain.
 17. The device inaccordance with claim 6, wherein the connecting device (10) is forinserting and clamping in place with electrical contact at least one ofthe heater cord ends (3.5, 3.6), and on a side facing the connectingdevice (10) a cover element (4.38) has formed-out places which worktogether with the connecting device (10) so that clamping in placeoccurs while putting the shell elements (4.31, 4.38) together.
 18. Thedevice in accordance with claim 1, wherein the connecting unit (4) isfixed in place on the base heating element (2) by fixing in place atleast one of the associated connecting cable end and at least one cordend (3.5, 3.6).